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Kawamura, Shunsuke; Naoe, Takashi; Ikeda, Tsubasa*; Tanaka, Nobuatsu*; Futakawa, Masatoshi
Advanced Experimental Mechanics, 4, p.33 - 37, 2019/08
A mercury enclosure vessel made of stainless steel is used as a spallation target in the pulsed spallation neutron source at J-PARC. It is severely damaged by the cavitation induced with pressure waves in association with the pulsed proton beam injection. A double-walled structure with a narrow mercury channel was adopted in the front end of the target vessel to reduce the cavitation damage. It has been experimentally demonstrated that the cavitation damage could be mitigated in the narrow channel but its mechanism has been unclarified yet. In this study, we investigated the cavitation from growing to collapsing through visualizing the spark-induced cavitation bubbles under flow field using a high-speed video camera. Furthermore, we measured the wall vibration due to the cavitation bubble collapse with changing flow velocity parametrically. It was found that the microjet collided perpendicular to the wall in the stagnant flow condition while it collided with an inclined angle from the perpendicular direction, suggesting that the collision pressure on the wall was reduced by flowing.
Nakamura, Hideo; Shibamoto, Yasuteru; Anoda, Yoshinari; Kukita, Yutaka; Mishima, Kaichiro*; Hibiki, Takashi*
Fifth World Conf. on Neutron Radiography, 0, p.665 - 672, 1996/00
no abstracts in English
4, 1994, Tokai, JapanJAERI-Conf 95-006, 207 Pages, 1995/03
no abstracts in English
Kawamura, Shunsuke; Naoe, Takashi; Ikeda, Tsubasa; Tanaka, Nobuatsu*; Futakawa, Masatoshi
no journal, ,
A mercury enclosure vessel made of stainless steel is used as a spallation target in the pulsed spallation neutron source at J-PARC. It is severely damaged by the cavitation induced with pressure waves in association with the pulsed proton beam injection. A double-walled structure with a narrow mercury channel was adopted in the front end of the target vessel to reduce the cavitation damage. It has been experimentally demonstrated that the cavitation damage could be mitigated in the narrow channel but its mechanism has been unclarified yet. In this study, we investigated the cavitation from growing to collapsing through visualizing the spark-induced cavitation bubbles under flow field using a high-speed video camera. Furthermore, we measured the wall vibration due to the cavitation bubble collapse with changing flow velocity parametrically. It was found that the microjet collided perpendicular to the wall in the stagnant flow condition while it collided with an inclined angle from the perpendicular direction, suggesting that the collision pressure on the wall was reduced by flowing.
Kawamura, Shunsuke; Naoe, Takashi; Tanaka, Nobuatsu*; Futakawa, Masatoshi
no journal, ,
A mercury target for spallation neutron source has been in operation at the J-PARC. When the high-intense proton beams hits the mercury to produce spallation neutrons, pressure waves are generated due to the abrupt heat deposition of mercury. Mercury enclosure vessel made of stainless steel with a thin wall thickness of 3 mm is severely damaged by pressure wave-induced cavitation erosion. Recently a double-walled structure with narrow gap channel at the front part of the vessel has been developed to mitigate the cavitation damage. In this study, we observed experimentally the growth and collapse behavior of cavitation bubbles in the narrow channel by using a technique of spark discharge in water and a high-speed video camera. Furthermore, the effects of flow velocity and gap width on collapsing pressure were investigated with focusing on the ratio of the projection radius to the gap width. The relationship between the narrow gap and the collapsing pressure will be discussed.
